Heat exchanger tube support and tube assembly



Jan. 30, 1968 P. 3. DOROSZLAI 3,366,172 HEAT EXCHANGER TUBE SUPPORT AND TUBE ASSEMBLY Filed Jan. 14, 1966 :2 Sheets-Sheet 1 Fly 1 In l/enfor:

/// TOR 5Y5 PAL evncw o Jan. 30, 1968 P. G. DOROSZLAI 3,366,172

HEAT EXCHANGER TUBE SUPPORT AND TUBE ASSEMBLY 2 Sheets-Sheet Filed Jan. 14, 1966 INVENIOR.

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United States Patent 3,366,172 HEAT EXCHANGER TUBE SUPPORT AND TUBE ASSEMBLY Pal Gyiirgy Doroszlai, Bassersdorf, Zurich, Switzerland,

assignor to Sulzer Brothers, Limited, Winterthur,

Switzerland, a corporation of Switzerland Filed Jan. 14, 1966, Ser. No. 520,559 Claims priority, application Switzerland, Jan. 21, 1965, 885/65 8 Claims. (Cl. 165-162) ABSTRACT OF THE DISCLOSURE A pair of opposed walls of the heat exchanger are provided with inwardly directed flanges which extend to the straight finned sections of the tube sections so as to confine the rising gas to the finned sections. The tube panels are secured in alternating manner to the top surfaces or bottom surfaces of the flanges.

This invention relates to a heat exchanger tube assembly having a plurality of tubes subject to an external cross flow of a gaseous heat carrier.

It is desirable that the gases discharged from heat exchangers which are positioned in the flow ducts of the hot gases to be cooled, such as, the heat exchangers employed as the reactor cooling medium of a gas cooled nuclear reactor, be discharged with a uniform temperature over the cross section of the discharge area. Therefore, it is necessary that the gas particles of each stream of flow give up approximately the same amount of heat at the end of their passage through the heat exchanger.

It has been known that in order to increase the flow resistance and to improve heat transfer, the pipes of the heat exchanger which are surrounded by the flow of gas have been provided on their straight sections with fins, for example, circular or helical fins, arranged at right angles while the reversing bends which join the straight sections into pipe coils have no fins.

However, in order to insure a uniform distribution of the final gas temperature, it has been necessary to limit the gas flow substantially to the pipe sections provided with fins.

Heretofore it has been proposed to solve this problem by suspending the finned pipe sections from longitudinal members which are welded to the pipes near the reversing bend. The longitudinal members form tight or nearly tight walls so that the gas flow which surrounds the pipe coils does not flow around the reversing bends. However, this design is relatively complicated and therefore relatively costly.

This invention solves the same problems of the prior art in a much simpler and more efficient manner.

Generally, the invention provides a heat exchanger tube assembly for interposition in the flow path of a gaseous heat carrier which includes a flow duct housing and a plurality of coiled tube stacks secured within the housing. The flow duct housing has a pair of opposed walls each of which is provided with a plurality of carrying flanges projecting into the interior of the housing at substantially right angles to the flow path of the heat carrier and a removable wall secured to the flange carrying walls for the purpose of assembly and accessibility to the coiled tube stacks. The carrying flanges on each opposed wall are arranged in an offset pattern with respect to the carrying flanges on the opposed wall. Each coiled tube stack which includes a plurality of straight tube portions joined together by reversing bends is secured to the top or bottom surface of the carrying flanges of the opposed walls in alternating manner with respect to the adjacent coiled tube stack in order to prevent the carrying flanges 3,366,172 Patented Jan. 30, 1968 from causing a spatial obstruction of the securement of the tube stacks. That is, where one coiled tube stack is secured to the bottom surface of the respective carrying flanges, the adjacent coiled tube stack is secured to the top surface of the same carrying flanges. Further, the carrying flanges are secured to the coiled tube stacks to the extent of the juncture of the respective reversing bends and straight tube portions.

In order to facilitate the securement of the coiled tube stacks to the carrying flanges, saddles are provided on the carrying flanges to engage the coiled tube stacks. Also the straight tube portions are each provided with suitable fins for the purposes above noted.

Where such is desirable, the mechanical strength of the housing walls may be increased by using corrugated sheets. It is also possible to achieve a particularly closely spaced arrangement of the finned tubes by using the offset arrangement of the coiled tube stacks.

Accordingly, it is an object of the invention to provide a heat exchanger tube assembly having a plurality of coiled tube stacks arranged in alternating offset manner.

It is another object of the invention to provide a heat exchanger tube assembly having a plurality of coiled tube stacks arranged in alternating offset manner.

It is another object of the invention to provide a heat exchanger tube assembly with carrying flanges projecting into the interior thereof at right angles to the flow direction of a heat carrier for securement of a plurality of coiled tube stacks thereto.

It is another object of the invention to provide a heat exchanger tube assembly with carrying flanges on a pair of opposed interior walls of the assembly arranged in an offset pattern with respect to the flanges on the opposed interior wall for projection into the interior of the assembly at right angles to the flow direction of a heat carrier for securement of a plurality of coiled tube stacks thereto.

It is another object of the invention to provide a heat exchanger tube assembly having finned tube portions which confines the flow of heat carrier therethrough to the finned tube portions in order to maintain a uniform temperature over the cross section of the discharge area of the assembly.

These and other objects and advantages of the invention will become more apparent from the following detailed description and appended claims taken in conjunction with the accompanying drawings in which:

FIG. 1 shows a cross section along the line 1-1 of FIG. 2 of a heat exchanger whose pipe bundle is subdivided into individual, parallel, plane pipe coils and is located in a flow duct which carries a heat medium, for example a gas.

FIG. 2 is a plan view of FIG. 1, partially in section.

FIG. 3 is a section along the line III-III of FIG. 1.

FIG. 4 illustrates a fragmentary view of the mounting of the pipe coils in the heat exchanger of FIG. 1.

FIG. 5 illustrates a perspective view of a saddle.

FIG. 6 illustrates a view taken on line 66 of FIG. 7 of a modified heat exchanger of the invention having corrugated walls; and

FIG. 7 illustrates a view taken on line 77 of FIG. 6.

The heat exchanger shown in the embodiment example is intended for fitting into the reactor plant of a gas cooled nuclear reactor. The coiled tubes 3 of the tube bundle through which the heating steam flows are fitted into a flow duct housing 1 of rectangular cross section which is open at the top and bottom. In this flow duct housing 1 the reactor cooling medium, for example CO which carries the heat, flows in the direction of the arrow A (FIG. 1), so that the tubes 3 are subject to a cross flow by the gaseous heat carrier. Several of such flow duct housings are located adjacently in a pressure vessel in an actual embodiment of such a reactor plant.

To indicate the dimensions of the heat exchanger it is noted that a single flow duct housing of this type may be 2 x 2 x 10 m. and may have a weight of more than 100 tons.

The wall 2 of the duct housing 1 is detachable and is secured with the screws 6 to two fixed walls of the housing 1, these walls being located opposite each other.

The straight, parallel tube sections 3 are provided with circular fins 7 and are joined to each other with finless reversing bends 8 to form plane, parallel tube stacks through which the medium to be heated flows in parallel upwards from below as indicated by the small arrows in FIG. 1.

The pipe stacks which are located vertically adjacent in the duct 1 are secured to the carrier flanges 4 with saddles 5. The carrier flanges in turn are welded, parallel to each other and at a certain spacing, onto those walls of the duct 1 which adjoin the wall 2 while the carrier flanges are arranged in offset relation to each other on the two walls.

Referring to FIGS. 3, 4 and 5, the individual tube stacks are also arranged in an offset relation to each other and are retained by the saddles alternately from above and below. Each saddle is formed with a pair of outwardly extending flanges each of which has a bore 12 (FIG. 5) for the passage of a bolt 11 (FIG. 4). Each saddle also has a side 14 which is turned towards a fixed wall of the housing 1 and which is shaped with a lightly upward bend to adjust to a pipe bend 8. The saddles 5 are secured to the carrier flanges 4 over the coiled tube stacks in a manner whereby a single bolt 11 passes through a bore 12 of a saddle on top of the flange 4 and a bore of a saddle on the bottom of the flange 4 and a nut 13 is threaded on the bolt 11 to secure the respective saddles in place, The saddles 5 are thus arranged across the carrier flanges 4 in an alternating above and below manner (FIG. 4). The depending saddles thus act as supports for the coiled tube stacks. The subdivision of the tube bundle into plane, parallel tube stacks results in individual passages which may extend in a diagonal direction through the tube bundle and through which vibration damping rods are pushed between the pipes 3.

These vibration damper rods 10 are provided to dampen out tube vibrations which may be caused by the gases which flow transversely against the tubes. These rods are of known structure and use as described in copending US. patent application Ser. No. 531,178, filed Mar. 2, 1966 and need not be further described.

The arrangement of the carrier flanges 4 at right angles to the direction of flow of the gas ensures effective throttling of the gas flow in the zone of the reversing bends so that the gas flow extends substantially in the zone of the straight tube sections provided with fins. In this way a temperature distribution of the gas which is uniform over the cross section is obtained in a simple manner at the end of the heat exchanger.

Installation of the tube bundle is effected with the side walls 2 of the duct 1 detached in that the previously manufactured tube coils are pushed into the flow duct 1 one after the other in a direction parallel to the carrier flanges 4 and are secured on these carrier flanges with the aid of the saddles 5. Finally, the side wall 2 is secured which in the example shown is bolted with the screws 6 onto the walls provided with the carrier flanges 4. After installation of the tube stacks it is also possible for the wall 2 to be welded to the adjoining walls of the duct housing 1.

Referring to FIGS. 6 and 7, wherein like reference numerals have been used to indicate like parts above, the walls of the housing 1 are formed in another embodi ment from sheets in a corrugated manner in order to increase the mechanical strength of the walls. The remainder of the heat exchanger is similar to that described above.

Having thus described the invention, it is not intended that it be so limited as changes may be readily made therein without departing from the scope of the invention, Accordingly, it is intended that the subject matter described above and shown in the drawings be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. A heat exchanger tube assembly for interposition in the flow path of a gaseous heat carrier comprising a flow duct housing interposed in the flow path of the heat carrier, said flow duct housing having a pair of opposed walls,

a plurality of carrying flanges secured to each of said opposed walls, said carrying flanges projecting into the interior of said housing at substantially right angles to the flow path of the gaseous heat carrier, and a plurality of plane coiled tube stacks secured in alternating manner to the top and bottom surfaces of said carrying flanges in said housing, each of said coiled tube stacks being staggered with respect to an adjacent tube stack and having a plurality of straight tube portions, a plurality of reversing bends joining said straight tube portions together in a single plane parallel to said pair of opposed walls, and a plurality of radially extending fins on each of said straight tube portions, said carrying flanges being secured to each said coiled tube stack to the extent of the juncture of said reversing bends and said straight tube portions whereby the flow path of the gaseous heat carrier is confined to said finned straight tube portions so as to maintain a uniform temperature over the cross section of the discharge area of the tube assembly.

2. A heat exchanger tube assembly for interposition in the flow path of a gaseous heat carrier comprising a flow duct housing interposed in the flow path of the heat carrier, said flow duct housing having a pair of opposed walls;

a plurality of carrying flanges secured to each of said opposed walls and projecting into the interior of said housing at substantially right angles to the flow path of the gaseous heat carrier; and

a plurality of coiled tube stacks secured on said carrying flanges in alternating manner to the top and bottom surfaces of said carrying flanges for preventing said carrying flanges from causing a spatial obstruction to the securement of said tube stacks, each of said coiled tube stacks having a plurality of straight tube portions, a plurality of reversing bends joining said straight tube portions together, and a plurality of radially extending fins on each of said straight tube portions, said carrying flanges being secured to each said coiled tube stack to the extent of the juncture of said reversing bends and said straight tube portions whereby the flow path of the gaseous heat carrier is confined in said finned straight tube portions so as to maintain a uniform temperature over the cross section of the discharge area of the tube assembly.

3. A heat exchanger tube assembly as set forth in claim 1 wherein said carrying flanges on each one of said opposed walls are arranged in an offset pattern with respect to said carrying flanges on the other of said opposed walls.

4. A heat exchanger tube assembly as set forth in claim 2 wherein said carrying flanges are parallel to each other.

5. A heat exchanger tube assembly as set forth in claim 3 wherein adjacent coiled tube stacks are secured in alternating manner to the top and bottom surfaces of said carrying flanges.

6. A heat exchanger tube assembly as set forth in claim 5 further comprising a plurality of saddles secured on the top and bottom surfaces of each of said carrying flanges for securing said coiled tube stacks thereon.

7. A heat exchanger tube assembly as set forth in claim 3,267,914 8/ 1966 Connell 122-510 1 further comprising a removable Wall secured to said 3 277 95 10 19 Taylor et 1 165 1 3 X pair of opposed walls for facilitating assembly of said tube stacks in said flow duct housing. FOREIGN PATENTS 8. A heat exchanger tube assembly as set forth in claim 5 7 wherein each of said opposed walls and said removable 818O28 8/1959 Great Bntam' Wall is corrugated.

References Cited ROBERT A. O LEARY, Przmary Examzner. UNITED STATES PATENTS A. W. DAVIS, JR., Assislant Examiner.

2,278,086 3/1942 Lea 165-82 

